Most fluid or semi-solid materials, such as meat and dairy products, react with the Reagent Dye Solution used in Protein testing very quickly.

When samples react with reagents slowly or components extract slowly, physical agitation will sometimes speed the process. The React-R-Shaker permits simultaneous, vigorous shaking of up to 44 samples in the 60 ml polyethylene sample bottles. When faster reaction is needed, the Reactor-R-Mill with a React-R-Tube may be used.

The React-R-Tube used with the React-R-Mill provides both tremendous agitation of the solution and a milling action that rapidly reduces the particle size of the solids. Since methods used by UDY involve relatively fast reactions, the milling action greatly accelerates the reaction rate by minimizes the need for permeation or diffusion through large particles to reach reactive sites. For example, wheat ground with a 1.0 mm screen in the Cyclone Sample Mill will reach equilibrium with shaking in the React-R-Shaker in about one hour. In contrast, by using the React-R-Tube and high speed Reactor-R-Mill, the reaction is completed in less than one minute.

The extraction or reaction time used is very important. If too little time is used, the extraction or reaction may be incomplete. Excessive times are unproductive and in the case of Protein tests, may cause other problems. If in doubt about the time required, start with a short time, and gradually increase it until consistent results are achieved. Allow a slight margin above the minimum time in case some samples react more slowly. Inconsistent or poor replication of results can be caused by incomplete reactions.

The tables of reaction times for solid commodities are based on use of the high-speed (3450 rpm) React-R-Mill. Use of the slow-speed (1725 rpm) Reactor-R-Mill or a React-R-Tube with the React-R-Shaker requires about 4 times longer. Units operated on 50 Hz power operate at 5/6 the speed of the 60 Hz units and require approximately 40% longer reaction or extraction times.

Some samples do not wet readily or otherwise mix with the reagents. The sample should be checked to ensure that complete mixing has occurred with samples such as non-wetting powders and grated cheese.

Reactor-R-Mill And React-R-Shaker

Initial Set-Up


Locate the unit near the UDY Colorimeter for convenience. Care should be taken not to obstruct the ventilating openings at the rear of the housing in order to avoid overheating.

Make certain that the power toggle switch is in the OFF positions before plugging the power cord into a grounded outlet. The voltage and frequency are shown on the Model and Serial No label on the back of the unit.

Model Speed RPM
(60 Hz Power source)
Speed RPM
(50 Hz Power source) High Speed
React-R-Mill 3450 N/A
Low-Speed React-R-Mill 1725 1425
React-R-Shaker, 0-5 minute Timer 1725 1425
React-R-Shaker, 0-60 minute Timer 1725 1425

Use of Timer(s)

The timer provides an automatic shutoff. Normally, the toggle switch is left in the ON position. It can be used to stop the shaking quickly if necessary. The React-R-Shaker has two timers. Use the 5 minute timer with the Extract-R-Tube and the 60 minute timer with the Shaker Trays.


The React-R-Tube contains a stainless steel pestle. It is free to slide back and forth between the ends of the React-R-Tube. The impact of the pestle with the sample-reagent mixture and the ends of the tube force reagent into the pores of sample particles and further mills the sample into smaller particles.

Normally, the reagent or extracting solvent should be added followed by the sample and, if appropriate, Filter Aid. This minimizes powdered sample wetting problems.

The longer portion of the React-R-Tube should enter the clamp from the right side. The screw clamp must be very tight to hold the React-R-Tube in place during shaking.

The vent screw on the long end of the React-R-Tube must be sealed during shaking. Only a little force is required to seal the vent. Excess force may break off the screw. Loosen the vent screw only when ready to begin filtration directly from the tube. Retighten it when filtration is complete.

The React-R-Tube solid cap is used during shaking of samples. It is replaced with a filter cap with a hole for direct filtrations. A filter disk support and then a 25 mm filter disk is placed inside the cap. If insufficient solutions filters through the opening, Filter-Aid needs to be added to the sample. Filter-Aid can be added before reaction or just before filtration. Solution filtered directly from the Reactor-R-Mill or Shaker usually comes out in large drops. Sufficient volume for measurement is normally contained in 10 to 15 drops.

Rinsing or washing the React-R-Tube between Protein test samples is not necessary and will cause problems if precautions are not followed. After an analysis, leave the residual solution in the tube until it is to be used for the next test. If this will be more than a few minutes, replace the filter cap with the solid cap. Just before reuse, pour and shake out as much solution from the last test as possible. Wipe off the React-R-Tube threads and filter cap. The solid cap should be wiped out after it is removed. A small amount of solution remaining in the tube will not significantly affect the following test.

If a React-R-Tube used for Protein testing is washed for some reason, rinse it out with "Working" Reference Dye Solution before reusing it. DO NOT, however, allow detergent or solvents to remain in either the React-R-Tube during non-use periods.

Because appreciable heat is generated during sample shaking in the React-R-Tubes, the temperature of the mixture should be taken each time a protein test is made. When a series of tests are being made at regular time intervals, the temperature may stabilize making measurement of each sample unnecessary.

The sound made by the React-R-Tube provides clues to the proper operation. With care, the individual impacts of the stainless steel pestle with the ends of the React-R-Tube can be heard. If these impacts are not occurring, the wrong volume of liquid may be being used (30 ml is the minimum volume and 40 ml is the maximum). As the React-R-Tube wears, it will make more noise and may not react samples completely. When the tube is held vertically, there should be very little sideways movement of the pestle as the tube is tilted. Replace the React-R-Tube when it becomes significantly noisier, shows other signs of wear, or fails to react or extract sample within the specified time period. New tubes for protein are translucent but rapidly discolor due to dye stains and sample residue buildup. This does not affect operation.


Shaker Trays

Place the Shaker Tray on a bench top, and push the 60 ml Sample Bottles down as far as possible into the holes. The bottles will remain in place by friction.

After the bottles are in place, a series of samples can be added, reagent added, and solid caps screwed on firmly. With the Shaker Arms in place, the trays can be secured using a 7/16 inch nut driver. By using both trays, forty-four samples can be reacted simultaneously on the React-R-Shaker. Before shaking with the React-R-Shaker, shake vigorously by hand. Check to see that all the sample particles are completely wet. Do not run the React-R-Shaker in its high speed (0-5 minute timer) mode while using

shaker trays. When less than 44 samples are being shaken, both trays should be attached and the load balanced between sides.

The Shaker Arms are held in place by the React-R-Tube clamps. Make sure the arms are centered so that trays will not hit the React-R-Shaker during operation. Slots in the tray permit insertion and removal of trays without having to fully remove the bolts which support the trays in place.

Use of Other Sample Containers

For Protein testing, if use of the React-R-Tube is not required for rapid reaction, simple hand shaking in the 60 ml Sample Bottle may be adequate (i.e. liquid milk and whey testing).


UDY Methods employ a variety of filtration techniques to separate solids from liquids. The best technique will vary with the type of test and sample. Specific procedures provide recommendations for the most convenient techniques for typical samples. A brief description of the techniques used and information about them follows.

Handling filter disks may, at first, seem difficult and time consuming. Experience leads to fast and easy handling of the disks. A good way to handle them is to take a group from the tube and gently "fan" them to separate the individual disks. In separating the disks by "fanning", handle them so that a leaning stack is formed. When the stack is placed so that it leans way from you, the thumb can be used to hold the front edge down while the index finger is used to lift and separate the top disk from the stack. Once an individual filter is obtained, it is positioned in the center of its holder. Use care while inserting the filter disk so that it goes into position centered and is not folded or torn.

Common cellulose filters papers react with and bind the dye used in Protein tests. They cannot be used in place of the fiberglass filter disks as supplied by UDY.

Whenever a liquid is filtered, it should appear clear. For Protein tests there are no exceptions to this. A cloudy filtrate will lead to low and erratic readings. To verify that the cloudiness is not due to a ruptured filter disk, the liquid can be filtered again through a second filter.

Direct Filtration from React-R-Tube

To filter directly from a React-R-Tube, a filer cap with a filter disk and support replaces the solid cap. Tighten the filter cap sufficiently to prevent leakage around the filter disk and into the cap threads. Stand the React-R-Tube on its short end where the filtered drops can fall into the UDY Colorimeter cuvet. Loosen the vent screw and liquid will begin filtering from the React-R-Tube. When sufficient liquid has filtered from the React-R-Tube, close the vent screw. If the tube isn't going to be used for awhile, replace

the filter cap with the solid cap. When the React-R-Tube is to be reused, shake out as much liquid as possible, then wipe the threads with a tissue.

If filtration is too slow, or insufficient liquid filters out, addition of filter aid prior to filtration should help. Use of a perforated filter support disk also improves the filtration efficiency. The support disk is positioned in the filtration cap before insertion of the filter disk. When support disks are used, they should be washed and dried between use.

For Protein testing, do not wash or rinse the tube. If it is ever washed, it must be rinsed with "Working" Reference Dye Solution before reuse.

Filtration From 30 or 60 ml Sample Bottles

Filtration from 30 or 60 ml Sample Bottles uses 19 m fiberglass filter disk with dropper caps to hold the filter disks. The bottle is squeezed gently to filter liquid from the bottle into the UDY Colorimeter cuvet. Excessive force may rupture the filter disk. A ruptured filter is often indicated by liquid being expelled in a stream rather than in drops. Difficulties with unusual samples can be minimized by use of Filter-Aid and using two filter disks.


Detail # 4 (Refer to Print "DET") yearly

  1. Motor - Relubricate with 30 drops of SAE20 non-detergent oil
  2. Detail # 13 Brass Inserts in clamp: Relubricate with DOW Corning Molykote G Paste or equivalent.
  3. Spring strip (Detail # 6) should be at a 90 degree to Motor Mount plate (Detail# 5)